Wilbur-Ellis Co. v. Kuther

Kuther (plaintiff) held a combination patent for a fish-canning machine and had authorized the original sales of several machines, receiving royalties. Wilbur-Ellis (defendant) bought four of these machines secondhand; three were inoperable and needed cleaning and repair of six of the machine's 35 patented components, after which the machines produced smaller, five-ounce cans instead of the original one-pound cans. Kuther sued for patent infringement; the district court and court of appeals both ruled for Wilbur-Ellis, and the case reached the Supreme Court.

Whether repairing unpatented components of a lawfully purchased combination-patented machine, in order to make the machine functional, constitutes patent infringement.